Keying system



Aug. 17, 1948.

D. PARSON, JR 2,447,088

KEYING' SYSTEM Filed June 5, 1946 TO KEIYED CIRCU IT KEYED gwwwwbob DONALD PERSON, JR,

DOT H DDR5? UTPUT Patented Aug. 17, 1948 UNITED STATES PATENT OFFICE KEYING SYSTEM Donald Parson, Jr., Framingham, Mass.

Application June 5, 1946, Serial No. 674,452

8 Claims. 1

This invention relates to a keying system useful in transmitting telegraph signals, and it is especially concerned with keying systems of the type in which dash signals are transmitted automatically so long as the key is held in one position and dot signals are transmitted automatically so long as the key is held in another position.

Keying systems of this general type are already known but some of these prior systems are rather complicated and require special power sources for the operation of vacuum tube elements, and other systems which do not employ vacuum tube elements involve the use of duplicate relay systems for transmitting the dot and dash signals.

An object of my invention is to devise a keyin system of the type described which is simple in construction, requires few parts, and is inexpensive to manufacture.

Another object of the invention is to devise a keying system of the type described which does not require the use of vacuum tubes with their special power supply sources but depends for its operation upon ordinary electromagnetic relays.

The keying system of my invention involves only two relays and three condensers in addition to the usual key and source of current.

According to the preferred form of my invention a transmitting relay is energized immediately when the key is moved to either position, and the energizing circuit of this relay is completed through normally closed contacts of a spacing relay which has a condenser shunted around its winding to prevent immediate closing of its contacts after its energizing circuit has been opened.

The spacing relay also has a condenser shunted around its normally closed contacts, and this second condenser serves to prolong the energization of the transmitting relay after the contacts of the spacing relay have opened. In the dash position of the key a third condenser is connected in parallel with the second condenser to still further prolong the time of energization of the transmitting relay after the contacts of the spacing relay have opened. In the dot and neutral position of the key, the third condenser is short-circuited to dissipate the charge thereon.

My invention is illustrated in the accompanying drawing in which Figure 1 is a circuit diagram schematically illustrating the preferred form of the invention; and

Figure 2 is a simplified diagram illustrating the same circuit arrangement shown in Figure 1 but adapted for use of a different type of key.

Referring to Figure 1 of the drawing the key is formed of two parallel switch blades I and 2 supported at their ends Ia and 2a. The outer ends of these blades are joined by a suitable insulating connection 3 having a forwardly extending finger piece 3a by which the blades I and 2 may be moved simultaneously to one side or the other of their normal positions. Blade I is normally positioned between a pair of fixed contacts 40. and 4b and blade 2 is likewise normally positioned between a pair of fixed contacts 5a and 5b. In the neutral position of the key the blades do not make contact with contacts 4a, Baand 517, but contact 41) engages blade I. This contact is mounted on a spring support so the blade I may be moved to the clot position, but a stop 42) prevents the contact 4b from following the blade to the dash position. A transmitting relay represented within the dotted rectangle 6 has an energizing winding 5a one terminal of which is connected to blade 2 and the other terminal being connected to a suitable so me of energizing current represented by the battery I. The other terminal of the source I is grounded or connected to a suitable return circuit. A spacing relay represented within the dotted rectangle 8 has an energizing winding 8a, one terminal of which is grounded and the other terminal is connected through contact 6b of relay 6 to source I. The contacts 81) of relay 8 are normally closed and serve to complete a connection from ground to fixed contacts 411, 5a and 5b of the key through conductor 8c. Fixed contact 4b of the key is grounded.

The circuit to be keyed is controlled by normally open contacts of relay 6.

A variable condenser CI is connected in shunt to the energizing winding 80. of relay 8, and while this variable condenser may be of any suitable construction, it is shown in the drawing as being formed of a plurality of small condensers Ca, Cb, Cc, etc., which may be connected in parallel by means of a rotary sector switch. 8. A second variable condenser C2 is connected from the conductor to ground, and this condenser may be constructed in the same manner as condenser CI. A third variable condenser C3 is connected from the blade I of the key to ground. The rotary switch blades of the condensers C i C2 and C3 may be connected together for simultaneous operation by any suitable mechanical means represented by the dotted lines Ill.

Operation of the arrangement shown in Figure 1 is as follows: Assume that the key is moved to the dot position, the circuit for energizing the transmitting relay 6 may be traced from source 3 'I through the winding 6a through blade 2 of the key to contact 52b through connection BC to contacts 8b of spacing relay 8 and to ground back to the other terminal of source 1. Completion of this circuit causes immediate closing of contacts to and 6c of transmitting relay 6. Contact 6b completes an energizing circuit for spacing relay 8, and contact 60 closes the circuit to be keyed. Relay B operates immediately and opens the original energizing circuit for relay 6 at contacts 81), but relay 6 does not release immediately because the opening of contacts 817 inserts condenser C2 in series with the relay winding Ga, and the charging of this condenser from the source 1 serves to-prolong the energization of relay after opening of the contacts 827. As soon as condenser C2 becomes charged to a predetermined amount, and its charging current diminished to a value insufficient to maintain relay ii in the operated position,

relay 6 releases, and the transmitting circuit is opened at contact 60. Also, the circuit oi spacing relay 8 is opened at contact 6b, but this relay does not release immediately by reason of the fact that the condenser Cl discharges through the winding 8a.

As soon as condenser Ci has discharged to a predetermined amount, contact to of relay 8 closes and reenergizes the winding 6a of relay 6 and also discharging condenser C2 (and C3 if on dashes) to repeat the cycle described above.

From the foregoing it will be understood that the duration of the dot signal will be determined by the value of condenser C2, and the duration of the interval between dot signals is determined by the value of condenser CI.

The operation of Figure 1 when the key is .moved to the dash position is the same as that described above for the dot position except that in this case condenser C3 is connected in parallel with condenser C2 by engagement of key blade l with the fixed contact to. This connection efiectively increases the capacity connected in series with transmitting relay winding 6a. when the contacts 811 of spacing relay 8 are open, and thereby increases the time interval during which the transmitting relay 6 remains energized. This connection does not increase the interval between successive dash signals, since this interval is determined by the value of condenser Cl alone.

In the "dot and neutral positions of the key, condenser C3 is short-circuited to dissipate any charge which may have been impressed thereon in the dash position of the key.

By varying the values of condensers CI, C2 and C3, any desired relation may be obtained between the length of the dot interval, the dash interval, and the space interval between signals. By providing for the simultaneous variation of these three condensers by the interlockil'lg control means represented at it, it is possible to adjust the keying circuit for fast or slow operation to suit different operators. For example, if one operator wishes to send at a relatively slow rate, the control ill would be moved in a direction to increase the values of condensers Cl, C2 and 03, whereas for an operator who transmits at a greater speed the control ill would be adjusted so that these condensers would have smaller values. The control Ill might be provided with a scale which would indicate the speed of operation in words per minute for any given setting.

Figure 2 is a simplified circuit diagram of the same circuit illustrated in Figure 1 with certain changes, and elements in this figure which perform the same function as elements in Figure 1 are indicated by like reference numerals. The maindifference between Figures 1 and 2 is in the arrangement for operating the key. In Figure 2, instead of using a finger extension mounted directly on the insulating connection 3 between the two key blades l and 2, the key is operated by means of a lever 3b pivoted at 30 and having one end connected to the insulating bar 3. The free end of the lever 3b is provided with a finger piece 3d by which the key is operated. Another slight change in Figure 2 from the arrangement shown in Figure 1 is that contacts 4a and 4b are arranged on opposite sides of the blade I.

The operation of Figure 2 is believed to be clear from the foregoing description of operation of Figure 1.

I claim:

:1. In a keying system, the combination of a transmitting relay having two sets of normally open contacts, a spacing relay having a set of normally closed contacts, a transmitting key having two transmitting positions, circuit connections controlled by said key in both transmitting positions for completing an energizing circuit for said transmitting relay through the normally closed contacts of said spacing relay, an energizing circuit for said spacing relay controlled by one set of contacts of said transmitting relay, a condenser shunted across the windings of said spacing relay to delay the release thereof, a second condenser connected across the contacts of said spacing relay to pro-long the energization of said transmitting relay after opening of the contacts of said spacing relay, and a circuit controlled by said transmitting key in one transmitting position for connecting a third condenser in parallel with said second condenser.

2. A keyin system according to claim 1 and including interlocking control means for simultaneously increasing or decreasing the values of said three condensers.

3. In a keying system, the combination of a transmitting relay having two sets of normally open contacts, a spacing relay having a set of normally closed contacts, a transmitting key having two transmitting positions, circuit connections controlled by said key in both transmitting positions for completing an energizing circuit for said transmittin relay through the normally closed contacts of said spacing relay, an energizing circuit for said spacing relay controlled by one set of contacts of said transmitting relay, a. condenser connected across the contacts of said spacing relay to prolong the energization of said transmitting relay after opening of .the contacts of said spacing relay, a second condenser, and a circuit controlled by said transmitting key in one transmitting position for connecting said second condenser in parallel with said first-mentioned condenser.

4. A keying system according to claim 3 and including interlocking control means for simultaneously increasin or decreasing the values of said two condensers.

5, In a keying system, the combination of a transmitting relay having a set of normally open contacts, a spacing relay having a set of normally closed contacts, a transmitting key having two transmitting positions, circuit connections controlled by said key in both transmitting positions for completing an energizing circuit for said transmitting relay through the normally closed contacts of said spacing relay, an energizing circuit for said spacin relay controlled by the normally open contacts of said transmitting relay, a condenser connected across the contacts of said spacing relay to prolong the energization of said transmitting relay after opening of the contacts of said spacing relay, and means controlled by said transmitting key in one position thereof for increasing the value of said condenser.

6. In a keying system, the combination of a transmitting relay having a set of normally open contacts, a spacing relay having a, set of normally closed contacts, a transmitting key having two transmitting positions, circuit connections controlled by said key in both transmitting positions for completing an energizing circuit for said transmitting relay through the normally closed contacts of said spacing relay, an energiz ing circuit for said spacin relay completed by the normally open contacts of said transmitting relay, and circuit connections controlled by said transmitting key for connecting different values of capacity across the contacts of said relay in different transmitting positions of said key.

20 Number REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date 2,235,627 Boor Mar. 18, 1941 

